1. Field of the Invention
The present invention relates to a power detection circuit and an RF signal amplification circuit having the same, and more particularly, to a power detection circuit that can adjust a voltage slope for power detection and an RF signal amplification circuit having the same.
2. Description of the Related Art
In general, in transmitting an RF signal, power of the RF signal amplified by an amplification circuit is detected and fed back according to the detection results to control the amount of amplification.
As a method of detecting power by extracting power from an RF signal, there is a closed loop method. The closed loop method extracts power by disposing a secondary conductor adjacent to a matching inductor of an RF signal using a coupling circuit. A sinusoidal waveform induced and extracted from the matching inductor is half-wave rectified using a diode, a ripple is removed using an RC filter, and a DC output is obtained from a voltage detection terminal.
In this power detection method, power is detected from the detected DC output using a voltage slope for power detection. At this time, system requirements are that the size of the voltage slope for power detection, that is, the slope should be satisfied, a detected voltage variation at a voltage standing wave ratio (VSWR) of 3:1 should be minimized, and a stable DC voltage should be extracted proportionally.
However, due to the diversity of characteristics and manufacturers of the systems, characteristics of the voltage slope for power detection are different according to the systems. In order to overcome this difference and meet the system requirements, the voltage slope suitable for the characteristics of each system is required, and for this, slope resistance for determining the voltage slope of each power detection circuit or device should be adjusted. Eventually, since the voltage slope is determined according to the characteristics of each system, the degree of freedom of the voltage slope is remarkably deteriorated and there is a difficulty in application to the system having different characteristics.